Josh Kenney, Melissa Hemling, and I just published an article in the October 2024 Journal of Chemical Education. The article describes inquiry-based activities that highlight the chemistry behind “No-Mess” picture-coloring books.¹ Well, it turns out that our timing is impeccable. That’s because the theme for National Chemistry Week 2024 (which happens in October) is “Picture Perfect Chemistry”. Our activity is a fantastic connection to this theme!

No-Mess coloring books make use of leuco (meaning colorless) dyes that become colored in the presence of acid (Figure 1).^1,2

Figure 1: Reaction between a colorless leuco dye and zinc ion (left) to form a colored complex (right)

Therefore, the dyes found in these markers act as acid-base indicators and can be used as such in a variety of chemistry demonstrations (Video 1).

Video 1: How Do Color Wonder Markers Work? Tommy Technetium YouTube Channel, June 2022.

As seen in Video 1, Crayola’s Color Wonder marking system has leuco dyes contained in markers. When these dyes contact zinc ions embedded in special Color Wonder marking paper, the dyes display their color (Figure 1). We recently discovered how to use solutions of Zn²⁺(aq) to develop the dyes in Color Wonder markers. What’s interesting about this is that Zn²⁺(aq) solutions develop the color of these dyes as vibrantly as the commercial system (Video 2. Please forgive me, the beginning of Video 2 is almost the same as that of Video 1).

Video 2: The Chemistry of Crayola Color Wonder Revealed, Tommy Technetium YouTube Channel, September 2024.

A fun part of the activity that we published involves having students discover how the Imagine Ink marking system works. In this system, a single marker can develop a variety of colors on special marking paper (Video 3).

I can't picture a more perfect activity for National Chemistry Week than our newly published article! #NCW https://t.co/ilWXsper7L pic.twitter.com/rXbHbOyFXF

— Tommy Technetium (@pchemstud) October 8, 2024

So how does the Imagine Ink marking system work? Well, if I told you, that would take the fun out of it, wouldn’t it? I encourage you and your students to explore the Imagine Ink marking system and figure out how it works! Maybe you’ll Picture the Perfect explanation to some Picture-Perfect chemistry!

Happy National Chemistry week and Happy Experimenting!

References:

1. Tom Kuntzleman, Josh Kenney & Melissa Hemling, Inquiry-Based Experiments with No-Mess Markers, J. Chem. Educ. 2024, 101, 10, 4523–4527.
2. Tom Kuntzleman & Dean Campbell, The Chemical Wonders of No-Mess Markers, J. Chem. Educ. 2022, 99, 6, 2364–2371.